Windows Application and classes

I've made a program in a conosle prompt and I'm trying to make it into a windows application. In the console program I have a class called "codons". I was wondering if you could tell me where should I place that class and how would I allow it to access controls like a textbox or richtextbox. Also, I'm trying to make an array of 21 objects. I defined the array and its places in the Main() function, but my program still can't find it. It says its not part of the namespace. Help...